Photographic silver halide emulsion containing a supersensitising combination

ABSTRACT

The present invention relates to a photographic silver halide emulsion or emulsion layer which comprises a super-sensitising combination of (1) a bis-benzothiazole or other bis-azole trimethincyanine dye and (2) a bis-benzimidazole trimethincyanine.

United States Patent [191 Thurston et a1.

[ PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING A SUPERSENSITISING COMBINATION Inventors: Elvin Frederick William Thurston;

John Gabriel Valentine Scott, both of Ilford, England Assignee: Ilford Limited, llford, Essex,

England Filed: Apr. 18, 1973 Appl. No.: 352,484

Foreign Application Priority Data [1;] 3,856,532 [4 Dec. 24, 1974 [58] Field of Search 96/124, 137

[56] vReferences Cited UNITED STATES PATENTS 3,666,480 5/1972 Shiba et a1. 96/124 3,718,475 2/1973 Shiba et a1 96/124 3,745,015 7/1973 Van Pee et a1. 96/137 Primary Examiner--J. Travis Brown v Attorney, Agent, or Firm-'-Wender0th, Lind & Ponack [57] ABSTRACT The present invention relates to a photographic silver halide emulsion or emulsion layer which comprises a super-sensitising combination of (1) a bisbenzothiazole or other bis-azole trimethincyanine dye and (2) a bisbenzimidazole trimethincyanine.

7 Claims, N0 Drawings PHOTOGRAPIIIC SILVER HALIDE EMULSION CONTAINING A SUPERSENSITISING COMBINATION tional sensitivity beyond that which can be regarded as the sum effect of the separate substances. Combinations of sensitising dye and other substances whichgive this better result are known as supersensitising combinations.

The present invention relates to a new 'supersensitising combination of the type just referred to.

According to the present invention there is provided a light sensitive photographic silver halide material which comprises a super-sensitising combination which consists of a sensitising dye of the formula R R3 7 R5 c=oH h oH-c X Rr r a -R& \N l ti R2 wherein R and R are each alkyl groups, or a group A-Q where A is a straight or branched alkylene chain stituted with at least one halogen, alkyl or alkoxy substituent, U is an anion and q is l in the case of a bctainclike molecular structure caused by the presence of a sulphonic acid or carboxylic acid group in R and is 2 in the case of a non-betaine-like molecular structure.

Preferably in the dyes of formula (2) R is a sulphoalkyl group.

It is to be understood that under certain conditions the dyes both of formula (1) and of formula (2) which contain either two carboxylic acid groups or two sulphonic acid groups may be present in the emulsion as a salt. Dyes of this type for example dye A as set forth below and dye l as set forth below are usually prepared as a salt and under certain conditions of coating the dye may be present in the coated emulsion still as a salt.

By lower alkyl group is meant an alkyl group containing 1 to 4 carbon atoms;

Preferably the sensitising dyes of formula (1) correspond to the formula containing 1-6 carbon atoms and Q is an amide, car- 1 boxylic acid or sulphonic acid group R R R and R are the same or different and each represent a hydrogen or halogen atom, or an alkyl, aryl, hydroxy or alkwherein R is an alkyl group and R is an alkyl, aryl, sulphoalkyl, hydroxyalkyl, carboxyalkyl, aralkyl or carboxybenzyl group, or an acylsulphamoylalkyl group of the formula (CH ),,SO NHCOR where n is an integer from 1 to 6 R is an alkyl group, or an alkyl or aralkyl sulphamoylalkyl group of the formula (CH S0 NI-IR where n is an integer from I to 6 and R is an alkyl or aralkyl group, O is a phenyl or phenyl subin formula (3) and (4) Y and Z have the above indicated meaning, R represents a lower alkylene groups, such as (CH R represents a lower alkyl or sulphoalkyl group, such as methyl, ethyl, sulphopropyl,

R a hydrogen atom or a lower alkyl group, such as methyl, R, a hydrogen atom, a lower alkyl or alkoxy group, such as methyl or ethoxy, 1R a hydrogen atom or a lower alkyl group, such as methyl, R, a lower alkyl or alkoxy group, such as methyl. or methoxy, R a lower alkyl group, such as ethyl and R,,' a lower sulphoalkyl group.

Preferably 0.01 g to 0.5g of each sensitising dye of formula l) and (2) per 1,5 g moles of silver present in the emulsion can be conveniently used.

The silver halide emulsion to which the supersensitising combination of dyes hereinbefore set forth may be added or may comprise any of the normal silver halide and halide mixtures used in photographic material for example silver chloride, silver bromide, silver iodobrov mide and silver chlorobromide. The emulsion binder may be gelatin or it may comprise other polymeric substances for example polyvinyl alcohol, polyvinyl pyrrolidone, ethyl cellulose or an alginate either alone or in admixture with the gelatin. There may be present in the emulsion layer a dispersion of a water-insoluble polymeric substance for example a polyacrylate or methacrylate.

3 4 The silver halide emulsion to which the supersensitis- Also in the Example the following dye of formula (2) ing combination of dyes hereinbefore set forth may be was used: added may contain the usual sulphur sensitisers for ex- Dye l. Anhydro-bis-[ l-ethyl-5-phenylsulphonyl-3- ample thiourea or thiosulphate and they may in addi- (3-sulphopropyl)-2-benzimidazole] trimethineyanine tion be sensitised with a noble metal, for example gold. 5 hydroxide, sodium salt, which has the formula:

Furthermore it may comprise polyethylene glycol sen- EXAMPLE sitisers and the usual tetraazaindene stabilisers and may The above dyes A B c and 1 were added to a high comam further Stablhsefs for example a m or speed silver iodobromide emulsion containing 5.4 mol mercury h emulslon l also comam Y per cent of silver iodide, after digestion of the emulment antlfoggants. The emulsion may also contain so- Sion, the quantity Shown for each dye being the amount lour Couplers filter dyes and acutance dyes per 1.5 g moles of silver halide. The emulsion was di- By use of the Combinati? of sfnsitisingdfis as just vided into portions, and each portion was coated onto set forth a valuable effect is obtained and is illustrated a film strip After exposure the Strips were developed by the Specific P and the realtive log speed of the emulsion were deter- In the Example whlch follows the followmg dyes of mined. The speeds are relative'log speeds measured to formula (1) used I light passing through a suitable filter, the term relative log speed being directly related to the logarithm of the ben'zoselenazoll fi'ethyhnmethmcyamne hYdmX'de reciprocal of the exposure in metre-candle-seconds re- Sodlum Salt Whlch has the formula quired to produce a density of 0.1 above fog. A higher TABLE Dye g Dyc g 50.1 50.] 50.1

(02" exposure (03" exposure /8" exposure through filter No. 204 through filter No. 404 to white light 1 0.1 3.09 4.01 B 0.03 1 0.07 4.09 130.02 1 0.08 3.30 C 0.2 .1 00 4.00 1 0.2 25 4.07 C 0.17 10.03 368 4.21 C 0.125 1 0.075 4.23

( S0 S0 figure indicates a higher speed. The filters used were 021-1, mcH 5 the tricolour green, No. 404 and the trlcolour red, No.

204 of the llford Colour Filters handbook.

These results show that when a combination of a dye of formula (1 andof formula (2) are present together L a; L e cnmsoi N4 ([93303 in the silver halide emulsion a useful increase in the red 1 s eed of the emulsion is obtained. B. Anhydro-[5-ethoxy-3-(3-sulphopropyU-2- Claim; benzothlfizolel. f y hy l. A photographic silver halide material which con- B- y m y hydroxldei Whlch has the tains a super-sensitising combination which consists esmula sentially of a sensitising dye of the formula (0 s C H r o-o1r 0 on 0 Y Z H I a 7 R7 R5 H5020 \e/ 0111 c=en e o1r c T a R. R. Xe (CH1)3SO3G C2115 \N N/ C. Anhydro-[3-(3-sulphopropyl)-2-benzothiazole] a (5 -methoxy-'3-methyl-2-benzoxazole) B-ethyltrir'nethmcyanme hydroxide which has the formula wherein R and R are each alkyl groups, or a group (7) S 0 A-Q where A is a straight or branched alkylene chain C4115 containing 1-6 carbon atoms and Q is an amide, cari (1-011: :c11=(1 I boxylic acid or sulphonic acid group, R R R and R 0o1n are the same or different and each represents a hydro- I gen or halogen atom, or an alkyl, aryl, hydroxy or alk- 7 011011401 (1111 I "oxy group, R is a lower alkyl group, Y and Z are each sulphur or selenium atoms or one is an oxygen atom and the other is a sulphur or selenium atom, X is an anion and p is l in the case of a betaine-like molecular structure caused by the presence of a sulphonic acid in either or both R and R or by the presence ofa carbox- 5 ylic acid in both R and R and is 2 in the case ofa nonbetaine-like molecular structure, together with a symmetrical trimethincyanine dye of the formula wherein R is an alkyl group and R is an alkyl, aryl, sulphoalkyl, hydroxyalkyl, carboxyalkyl, aralkyl or carwherein Y and Z have the meaning given in claim 1. R,

represents a lower alkylene group, R represents a lower alkyl or sulphoalkyl group, R represents a hyboxybenzyl group, or an acylsulphamoylalkyl group of the formula (Cl-l S0 NHCOR where n is an integer from 1 to 6 and R is an alkyl group, or an alkyl or aralkyl sulphamoylalkyl group of the formula (CH S0 Nl-IR where n is an integer from 1 to 6 and R is an alkyl or aralkyl group, Q is a phenyl or phenyl substituted with at least one halogen, alkyl or alkoxy substituent, U is an anion and q is l in the case ofa betainelike molecular structure caused by the presence of a sulphonic acid or carboxylic acid group in R and is 2 in the case of a non-betaine-like molecular structure.

2. A silver halide material according to claim 1,

wherein in the dye of the formula secondly set forth in claim 1 R is a sulphoalkyl group.

3. A photographic silver halide material according to claim 1, which contains a supersensitising combination which consists essentially of a sensitising dye of the formula together with a symmetrical trimethincyanine dye of the formula drogen atom or a lower alkyl group, R represents a hydrogen atom, a lower'alkyl group or a lower alkoxy group, R represents a hydrogen atom or a lower alkyl I group, R represents a lower alkyl or alkoxy group, R

represents a lower alkyl group and R represents a lower sulphoalkyl group.

4. A photographic silver halide material according to claim 3 the symmetrical trimethincyanine dye of which corresponds to the formula claim 1. 

1. A PHOTOGRAPHIC SILVER HALIDE MATERIAL WHICH CONTAINS A SUPER-SENSITISING COMBINATION WHICH CONSISTS ESSENTIALLY OF A SENSITISING DYE OF THE FORMULA
 2. A silver halide material according to claim 1, wherein in the dye of the formula secondly set forth in claim 1 R9 is a sulphoalkyl group.
 3. A photographic silver halide material according to claim 1, which contains a supersensitising combination which consists essentially of a sensitising dye of the formula
 4. A photographic silver halide material according to claim 3 the symmetrical trimethincyanine dye of which corresponds to the formula
 5. A silver halide material according to claim 1, which contains from 0.01 g to 0.5 g of each sensitising dye of the two formulae set forth in claim 1 per 1.5 g moles of silver present in the emulsion.
 6. A photographic silver halide emulsion which contains a supersensitising combination as defined in claim
 1. 7. A photographic silver halide emulsion layer which contains a supersensitising combination as defined in claim
 1. 